I put together PiMusicbox by hand on the Zero using Jessie Minimal and a USB sound card, and have documented the steps. You wouldn’t know its not the official. Web and everything.
I am doing mine as a project to put into a speaker casing, for a way more capable bluetooth speaker, with access to all my music, airplay, etc, etc, etc.
(First announced here, I am also working on an extension for Sirius XM Internet Radio support for Mopidy!)
Anyways, I have a bug with Mopidy not playing audio via the USB DAC (everything else does) but once that is fixed I would be happy to post my steps on everything I did to setup my Zero.
My bug if anyone is interested is posted at: [Solved] USB Dac Wont Play Through Mopidy But Works Everywhere Else